Presented by Doug Gapp Pipeline Safety Planning Dept Southwest Gas Corporation August 19, 2014 Western Region Gas Conference San Bruno Incident, September 9, 2010 Pipeline Hazardous Materials Safety Administration (PHMSA) Advisory Bulletin ADB 11-01, Jan 10, 2011 Evaluate risk – physical and operational characteristics California Independent Review Panel San Bruno (Recommendation 18.104.22.168), June 24, 2011 Program to collect…construction and operating data PHMSA 2011 Advanced Notice of Proposed Rulemaking (Section D), August 25, 2011 Requirements for collecting, validating, integrating and reporting pipeline data National Transportation Safety Board (NTSB), August 30, 2011 San Bruno 29 Recommendations Recommendations specific to Integrity Management Program (IMP) Completeness/Accuracy Integrity Management Program Data Federal legislation, January 3, 2012 Confirm material strength Pipelines operating in high-consequence areas (HCAs) Greater than 30 % specified minimum yield strength (SMYS) California Public Utilities Commission 17 Hazards Report (Item 4), March 14, 2012 Verifiable and traceable records PHMSA Integrity Verification Process Likely will require action on transmission pipe operating in HCAs and Class 3 and 4 locations Focus of NTSB, federal legislators, regulatory agencies Transmission pipelines HCAs Data – Know your pipelines so you can properly evaluate risk 1979 Acquired gas system from Tucson Gas and Electric 1984 Acquired gas system from Arizona Public Service November 2012 proposed field data collection initiative-wall thickness pilot Goal: improve knowledge and records of company pipeline characteristics Specifically: Collect wall thickness data where not documented Accurately classify pipeline Appropriate integrity management application Transmission Integrity Management Program (TRIMP) Distribution Integrity Management Program (DIMP) pipe that meets transmission classification by actual properties, not lack of records Conventional In-line Inspection (ILI) Other ILI tools Pipetel Explorer – Southern Nevada Division (SND) Dig and inspects (D&Is) Southern Arizona Division (SAD) • • Available for pipe sizes 6” to 36” • Wireless/battery operated • ~ 3300 foot range • Camera (front and back) • Remote Field Eddy Current Sensor (RFEC) • Magnetic Flux Leakage (MFL) • Maneuver through standard fittings Either live or de-gassed pipeline Explorer Project Las Vegas Successful launch and recover robotic tool (tetherless) Into a non-live natural gas pipeline Obtain wall thickness (WT) data Identify potential metal loss First SWG commercial application Crossing that prohibited conventional inline inspection tools from passing Pipeline diameter – 6-inch Maximum operating pressure (MOP) – 125 psig 5522 feet unconfirmed wall thickness (WT) Conservative assumption of 0.083 inches WT 21 feet 0.156 inches WT Specified Minimum Yield Strength (SMYS) unknown Conservative assumption of 24,000 psi 20.78% SMYS at MOP Vintages 1964, 1968, and 1972 • Originally planned for 3 bellholes, ended up with 4 • Tool run twice for each distance • Wall thickness data • Metal loss data Urban location traffic & noise Night work Crossing over storm drain Question: What if it gets stuck? Answer: Put a leash on the pig Manual Tether Pre excavate pits, larger than standard bellholes Horizontal launch Opted for out of service Night work due to heat of summer Reduce project complexity Heat impacted equipment (no flow to cool) Improvised air conditioning pipeline Anomalies No Immediate or Scheduled repair required No metal loss locations 7 suspected dents 3 suspected dents or material deposits Wall Thickness data Majority of pipe is 0.156 inches (11.1% SMYS) some 0.188 inches WT (9.2% SMYS) Not the 0.083 inches WT Validate data – field work Two locations for inspection Dent Lowest WT reading Updated WT attribute data Final follow-up with vendor Experience with Explorer tool Once confirmatory digs completed able to correctly classify pipe Avoided replacement Explorer cost between $200K-$300K per mile Compared to $2+ million/mile to replace Questions on Explorer project? Dig and Inspect (D&I) Project Yuma Pipeline Diameter – 6-inch Maximum Operating pressure – 150 psig 1.3 miles Unconfirmed wall thickness (WT) Conservative assumption of 0.083 inches 1.2 miles confirmed WT upstream classified as transmission Specified Minimum Yield Strength (SMYS) unknown Conservative assumption of 24,000 psi 24.9% SMYS 7 HCAs Vintages 1954, 1955 • 35 D&I Bellholes • Wall thickness data 1954 vintage changed to 0.250 wall – 8.3% SMYS 1955 vintage changed to 0.188 wall – 11.0% SMYS Cost Comparison Actual cost was approximately $50K Allowed reclassification 2.5 miles of pipe to highpressure distribution Lowered comparative risk Southern Arizona Division D&I: Yuma-Wellton Approximately 93,000 feet of 4-inch pipe unknown WT 2 HCAs Central Arizona Division Explorer ILI: Litchfield Ave Approximately 2500 feet of 6-inch pipe unknown WT Almost entirely in an HCA Pipe with: Unknown wall thickness? Operating at high % SMYS? Actual wall thickness likely higher? Unpiggable? Determining actual wall thickness: Lowers relative risk in HCAs Accurately classify pipe Appropriate integrity management application Questions???